Mark

8 comments By Mark

  • I love the Stille, when I had to make a bipyridine as part of an extraction agent (MF2BTBP or (MFBTBP2) I used the reaction of 2-bromopyridine and 2-tributylstannyl4-tertbutylpyridine as an early step. I rather like Stille and Wittig chemistry when I am making pyridines. The clever trick is to shake the reaction mixture with hydrochloric acid to extract all the pyridines as HCl salts. The neutral Bu3SnBr and PPh3PO stays in the organic layer.

    Commented on: 2019-10-07T16:38:05.140

    John Stille inventor of the still cross coupling standing in his office

    Stille cross-coupling

  • The article states "When ammonia becomes airborne, it quickly expands and forms a large cloud that acts like a heavier-than-air gas", the problem is that ammonia is lighter than air. The formula mass of ammonia is 17 grams per mole while the formula mass of air (assume air is 80 % N2 and 20 % O2) is 28.8 per mole. So ammonia gas will be 0.49 grams per litre lighter than air. I am sure that ammonia will tend to rise up into the air in a similar way to methane (FW = 16).

    Commented on: 2019-05-01T07:50:22.207

    A picture showing a chemical spill danger sign

    Anhydrous ammonia leak in the US hospitalises 38

  • It was aqueous sodium carbonate and not aqueous sodium chloride which was used to take the cobalt out of the DES and into a solid.

    Commented on: 2019-04-04T19:55:15.043

    An image showing a solution turning green as it pulls cobalt from a spent lithium-ion cathode

    Green solvent recovers in-demand metals from batteries

  • I think Bart is wrong, from what I recall Robin Hood took money from the rich and gave it to the poor. He also went about righting wrongs in the Nottingham area. To be Robin Hood you need to give to the poor !

    I do not see the copyright pirates doing something which is as public spirited as that. I am an editor of a open access journal (Cogent Chemistry) where while we might not steal from the rich we do give to the poor. Cogent chemistry offers reduced price and even free publication to the poorer authors.

  • Nice chemistry but there might be a problem.

    The problem is that the sulfur end product has the potential to be a rather nasty compound. The worst smelling sulfur compound which I have heard of with the strongest smell has to be either tert-butyl thiol or Me3SiSSiMe3. If the process forms Et3SiSSiEt3 then it might well convert the slightly offensive things like benzothiophene and dibenzothiophenes into something which has a lot of potential to be more mobile and offensive.

    The normal end product of HDS is to form hydrogen sulfide which can be scrubbed out of gas streams with zinc oxide or removed in some other methods such as combustion with a limited amount of oxygen to form SO2 which then reacts with H2S to form sulfur and water.

    I have never tried to work with Et3SiSSiEt3, but might have similar properties to the methyl compound and thus be quite horrible. An alternative to HDS (hydrodesulfurisation) is to use oxidation of the sulfur compounds to change their properties followed by some separation such as solvent extraction.

    Commented on: 2017-03-20T16:53:24.417

    Car exhaust fumes

    Squeezing the last of the sulfur from fuels

  • Regarding electric cars, I quite agree with Norman Groocock that in general the more energy conversions which occur then the lower the well to wheel efficency. From a climate change point of view it makes more sense to put DERV in a car or taxi rather than to burn the fuel oil to generate electric power which is then used to charge a secondary cell.

    I hold the view that a "zero emissions vehicle" is in fact an "emissions elsewhere vehicle". But I heard an interesting argument some years ago from an academic at a climate change lecture. This academic agreed that a diesel car would be better from a CO2 release point of view than an electric car running on fossil fuel produced electric power.

    But the academic argued that if we moved over to electric vehicles which are charged from the electricity grid then if the electric power production was done using systems which do not release carbon dioxide or other greenhouse gases into the air then it would be much better from a climatic change point of view.

    I think we need to look at the whole of the lifecycle of the equipment used for electric power production and energy conversion. For example lanthanides are needed for the magnets and other parts of some of these potentially greener systems. The problem is that lanthanide mining creates pollution, however lanthanide recycling should produce far less pollution. Thus it makes sense to do research on the recycling of materials such as the lanthanides. A similar argument can be made for some other materials needed in high tech or green equipment.

    Commented on: 2017-03-19T18:56:08.673

    0317CW - Letters

    Letters: March 2017

  • I am working in Sweden, I do admit that I pay a lot of tax but as a tax payer I think I get a better deal than I did when I was a tax payer in the UK.

    Commented on: 2016-11-28T18:24:38.310

    Sweden - Archipelago

    Sweden

  • Thank goodness for that, homopathic medicine in my view is a waste of money.